6 Answers
6

I’ve done it. I was able to underclock through the CPU speed jumpers, but you may have other options. i. e., the BIOS. Also, instead of discarding the fan altogether, I connected it to the 5-volt power source (may be a red wire, keep polarity in mind), but make sure the fan still runs, or at least starts every time you power up. You can also use a different fan that will still work with the 5 volts, but leave this step for last. Do the underclocking first.

When you first try any configuration, keep a finger on the heat sink. If it gets hot enough that you are not able to keep the finger on it for long, power down the machine immediately because that configuration doesn’t work. Also, keep case as open as possible, or heat will build up inside it, especially if it is warm where the computer is kept.

Wow! Awesome info, Thanks :) Good to know someone already tried it :D Yes, I might be able to underclock it through the BIOS since DFI builds mobos with overclockers in mind.
–
sHokkueibuOct 26 '09 at 12:37

You can probably get away with the stock cooler, but you do need a fan with it. I've got an Athlon XP 2500+ still in service and it gets quite hot.

Those were workhorse desktop CPUs when they were originally put on the market. If you want a fanless system, go with a modern low-power CPU (Atom or similar) that is designed for such an application.

Edit: You can certainly experiment. A (much) larger cooler will help. Underclocking the CPU will help (assuming BIOS supports for it) -- but it might not help enough.

If you're going to experiment, do so carefully, take temperature measurements often, and test out your system with copies of data that you can afford to lose.

Edit 2: TonyUser posts a table of maximum CPU temperatures that indicates the Athlon 64 3200+ can handle up to 70°C. Unless it's a Socket 939, which might be limited to 65°C -- you'd need to check the manual from AMD to be sure.

What if I underclocked it? If such a thing is possible
–
sHokkueibuOct 24 '09 at 18:08

may be possible depending on the motherboard, and may work depending on the workload you give it. you'd want something bigger than the stock cooler tho. maybe if you mount it in a freezer.... :)
–
quack quixoteOct 24 '09 at 18:10

Thank you. I'll post an update when I get some free time :D
–
sHokkueibuOct 24 '09 at 18:33

Do you know that by experience? I can find it here for €40 which is €10 more than I'm willing to spend.
–
sHokkueibuOct 25 '09 at 14:17

I do not know that by experience, but it's mentioned in the review: When the Hyper Z600 cooler was rotated 90 degrees, so that its aluminum fins were oriented vertically, the cooler failed the 150W test only. With an 85W heat load, and its aluminum fins pointing straight up, the Hyper Z600 heatsink was able to maintain a rise above ambient temperature of 56.5C passively. No fans, just convective air flow here folks. The processor you have is ~77W so with some airflow I think it should do just fine.
–
DaMaccOct 25 '09 at 16:11

With no fan at all, I doubt your CPU will last you very long. You existing radiator was not designed to function as a passive cooler, I would get a replacement / additional fan first. If you don't want to do that, get a larger radiator. There's a decent overview of cooling choices here.

You might want to look at this paper Athalon wrote on ways to measure your CPU temperature. It says the easiest way is to use software, but there is no one program that provides accurate data for all motherboards. There is a program out there Motherboard, that may provide accurate readings, but I've never used it. RealTemp is for Intel chips, doubt it would be accurate on an AMD.

Good point. I just assumed an old processor would be easier to cool with the coolers available nowadays. Yes, I have other stuff I'd like to invest in, this is just a way to use spare parts.
–
sHokkueibuOct 25 '09 at 12:46

Ah. You could rig up some kind of water-cooling system, it's not as cheap as a fan, but it can be pretty quiet.
–
PhoshiOct 25 '09 at 13:07

I tried it the hard way this week: my (boxed) cpu-cooler broke after one year, but PC worked for a few more days.
Without warning CPU overtemperature, since the CPU heatsink was big enough and very close to power supply air stream.

The passive cooled graphics adapter was not so lucky, it fried yesterday (that's when I noticed CPU fan fail) and took a part of Mainboard power supply with it:-(

I learned:

Use a silent (expensive) case fan and think about airflow before getting rid of CPU fan.